The present application is based on and claims the benefit of Korean patent application Serial Nos. 2001-65933, filed Oct. 25, 2001, the contents of which are hereby incorporated by reference in their entirety.
1. Field of the Invention
The present invention relates to a reciprocal hermetic compressor, and more particularly, to a connecting rod apparatus for connecting a crank shaft and a piston in a reciprocal hermetic compressor.
2. Description of the Related Art
Generally, as shown in FIG. 1, a hermetic compressor comprises: a motor 1 having a stator 2 and a rotor 4 rotatably disposed around the stator 2; a crank shaft 6; a connecting rod 8; and a piston 10. The crank shaft 6 is integrally rotated being connected with the rotor 4, and has an eccentric portion 6a at a lower part. A portion of great diameter 8a disposed at one end of the connecting rod 8 is connected with the eccentric portion 6a. A portion of small diameter 8b disposed at another end of the connecting rod 8 is connected with the piston 10. The piston 10 moves lineally in a piston chamber 12a in a cylinder 12. Referring to FIG. 2, the portion of great diameter 8a has a great inner diameter h1 connected with the eccentric portion 6a, and the portion of small diameter 8b has a small inner diameter h2 connected with a piston pin 11. The great inner diameter h1 and the small inner diameter h2 are connected by an oil transferring path 8c. 
In the above structure, the crank shaft 6 is rotated as the rotor 4 is driven, and allows the eccentric portion 6a to be rotated. The connecting rod 8 converts an eccentric rotation of the eccentric portion 6a to a lineal movement and reciprocally moves the piston 10. In other words, the reciprocal hermetic compressor is constructed to convert the rotation of the motor 1 to the lineal movement of the piston 10.
In the meantime, for the hermetic compressor having the above construction, an axis of the crank shaft 6 forms 90xc2x0 when crossing with the connecting rod 8. The angle of 90xc2x0 is known as a very important element in designing. Therefore, a geometric tolerance is generally written in related elements.
In addition, the piston 10 slides keeping an appropriate clearance in the piston chamber 12a in the cylinder 12. Yet, a parallel degree and a symmetry degree of the piston 10 should be regularly maintained centering the axis of the crank shaft 6.
Furthermore, the piston 10 should form a right angle with the piston pin 11. In the case of the connecting rod, the parallel degree and the symmetry degree between the great inner diameter h1 and the small inner diameter h2 are also important elements.
As described so far, various machinery connecting relations based on the connecting rod 8, in other words, an array of the connecting rod 8 with respect to the axis of the crank shaft 6 is an element affecting the driving capability of the compressor. Accordingly, when the array of the connecting rod 8 with respect to the axis of the crank shaft 6 is misarranged or instable, friction and abrasion between the elements are heavily generated. Therefore, the compressor might not be able to operate normally. Especially, when the crank shaft 6 and the piston 10 is not mechanically arrayed, the problem could be more aggravated.
Thus, there is a need to improve the reliability of the compressor by compensating for errors of the connecting rod apparatus that converts the rotation of the crank shaft 6 to the sliding.
The object of the present invention is to provide a connecting rod apparatus of a reciprocal hermetic compressor having an improved structure to compensate for the misalignment of a crank shaft and a piston.
The above object is accomplished by providing a connecting rod apparatus of a compressor for converting a rotation to a reciprocal sliding by connecting an eccentric portion of a crank shaft and a piston. The connecting rod apparatus comprises: a bush rotatably connected with the eccentric portion, and having a first connecting portion with a pair of sloping sides at an outer circumference, the sloping sides have a predetermined slope in regard to an axis of the eccentric portion; a connecting rod having a small inner diameter for being connected with a piston pin connected with the piston, the small inner diameter is formed at one end of the connecting rod, and a second connecting portion for being connected with the first connecting portion in a direction of the axis along the sloping sides, the second connecting portion is formed at another end of the connecting rod; and a connecting member for connecting the second connecting portion and the bush to be able to move by an external power.
It is preferable that the bush comprises: a cylindric body having a great inner diameter connected with the eccentric portion and the first connecting portion at an outer circumference; and a protrusion protruded corresponding to the first connecting portion at the outer circumference of the body and clamped by the connecting member.
Moreover, the second connecting portion includes: a pair of diverged portions diverged from one end of the body of the connecting rod in order to wrap the first connecting portion, and the pair of diverged portions have sloping sides corresponding to the sloping sides of the first connecting portion; and a supporting portion extended from a part between the diverged portion and the body by a predetermined thickness in order to prevent the connecting member from being separated by clamping both ends of the connecting member.
In addition, the second connecting portion is diverged from on end of the body of the connecting rod taking a shape of xe2x80x98Uxe2x80x99.
Furthermore, the sloping sides have an angle of 3xc2x0 to 5xc2x0 with respect to the axis of the eccentric portion.
Moreover, the connecting member is a piano string having a predetermined thickness in order to combine the connecting portion and the bush.
Additionally, the connecting member comprises: a clamping portion bent for a predetermined type in order to clamp the protrusion of the bush in a middle part; a plurality of supporting portions extended symmetrically from the clamping portion in order to wrap and support the outer circumference of the bush; and an end portion extended being bent from the supporting portions in order to wrap and clamp the second connecting portion of the connecting rod. The bush is prevented from being separated from the connecting portion by being supported by the piano string and can move by an elasticity of the piano string.